1. Field of the Invention
The present invention relates to a method of fabricating a semiconductor device and, more particularly, to a method of forming wires of a semiconductor device suitable for improving the performance of the semiconductor device.
2. Discussion of the Related Art
When aluminum is used to form wires of a semiconductor device, it is first deposited and etched in a chlorine plasma. Then a post-treating process is performed to prevent aluminum corrosion. In the post-treating process, the deposited aluminum is dipped into a distilled water to remove chlorine, so that the wires formed with aluminum are protected from corrosion.
As an alternative way of preventing such an aluminum corrosion, an in-situ H.sub.2 O vapor plasma is used to remove the chlorine. Most of aluminum etching equipments include an etching chamber and a H.sub.2 O vapor cleaning/ashing chamber, so that a H.sub.2 O vapor plasma can be used to prevent the corrosion without destroying the vacuum. When removing the chlorine in the H.sub.2 O plasma cleaning process, however, a photoresist which is used to form an etching pattern is also removed by the H ions, O ions, and OH ions. In addition, the H.sub.2 O plasma cleaning process chemically changes the material of the photoresist. As a result, a significant amount of polymer remainder remains on the wires made of aluminum or aluminum alloy, which is not removable with an O.sub.2 ashing process. Accordingly, additional processes are needed to remove the polymer remainder.
To remove the polymer remainder, it has been suggested to use a wet etch employing a solution such as ACT or EKC which contains an amine group, or a strong acid liquid solution. However, such a chemical treatment causes over-etching and inaccurate patterning of the aluminum layer, deteriorating the performance of the semiconductor device.
A conventional method of forming wires of a semiconductor device, which employs the above described process, will be explained below with reference to the accompanying drawings, in order to illustrate the problems of the conventional method.
FIGS. 1a through 1d show cross-sectional views for explaining a conventional method of forming wires of a semiconductor device.
First, as shown in FIG. 1a, a barrier metal layer 12 is formed on an insulating layer 11. On the barrier metal layer 12, an aluminum layer 13 (or an aluminum alloy layer) is formed to be patterned as wires. An anti-reflective coating (ARC) layer 14 is formed on the aluminum layer 13, and a photoresist layer 15 is formed on the entire surface of the ARC layer 14. The photoresist layer 15 is subjected to an exposure and development process for patterning.
As shown in FIG. 1b, in a plasma containing chlorine, the ARC layer 14, the aluminum layer 13 and the barrier metal layer 12 are etched using the patterned photoresist layer 15 as a mask. Then an in-situ H.sub.2 O vapor plasma cleaning process and an O.sub.2 etching process are performed to remove the insulating layer 11 to a predetermined depth.
As shown in FIG. 1c, as the photoresist layer 15 is removed the remainder 15a is produced on the ARC layer 14. A chemical liquid solution containing an amine group or a strong acid solution containing a sulfuric acid or a nitric acid is used to remove the remainder 15a. After the remainder 15a is removed, a distilled water process, a spin dry process and an N.sub.2 blowing process are performed.
As shown in FIG. 1d, when the above chemical treatment is performed, however, the aluminum layer 13 is over-etched because the etch rate of the ARC layer 14 is different from that of the aluminum layer 13. At the same time, the barrier metal layer 12 under the aluminum layer 13 is also over-etched, resulting in an inferior wiring pattern.
Accordingly, the conventional method of forming wires of a semiconductor device has problems including the following.
First, an extra bath is required because a chemical solution is used to remove photoresist/polymer remainders.
Second, because a wet etch using a chemical solution is performed to remove polymer remainders, the process time for forming the wires increases and the wires are further over-etched, deteriorating the performance of the semiconductor device having such wires.